1. Field of the Invention
The present invention relates to a fluid delivering system. More particularly, the present invention relates to an improved version of the fluid delivering system Unity 85DP provided by TEL Corporation, which system is capable of sensing abnormal pressure buildup inside its pipeline and terminating a current processing operation.
2. Description of the Related Art
In the manufacturing of semiconductors, many processing operations require the supply of gases to the processing chambers. For example, gases such as SiH.sub.4, B.sub.2 H.sub.6, NH.sub.3 and H.sub.2 are needed in chemical vapor deposition; gases such as CF.sub.4, CHF.sub.3, O.sub.2 and SF.sub.6 are needed in dry etching, and inert gases are used in various types of equipment and measuring instruments. Therefore, an independent gaseous dispensing system is often needed to deliver the processing gases. Since the properties of gases vary over a wide spectrum, the designs of gas delivering systems also range from simple to complex.
FIG. 1 is a schematic diagram showing a Unity 85DP pipeline system by TEL Corporation for delivering helium. As shown in FIG. 1, the pipeline system 10 is connected to a supply device 12, an operational device 14 and an extraction device 16. The pipeline system 10 includes a main pipeline system 18 and at least a secondary pipeline system (here, only a secondary pipeline system 20 is shown). First, a gas (for example, helium) is forwarded by the supply device 12 into the pipeline system 10. After passing through the main pipeline system 18 and the secondary pipeline system 20, the gas is delivered to the operational device 14. The operational device 14, for example, can be placed next to the lower electrode (ESC) inside a processing chamber so that a back surface of a silicon chip can be cooled by the gaseous helium. Finally, the gaseous helium is channeled away via the extraction device 16, which is, for example, a pump.
The main pipeline system 18 comprises a first flow valve 22, a first flow controller 24, a first pressure gauge 26, a second flow valve 28, a third flow valve 30, a fourth flow valve 32, a first pressure controller 34 and a fifth flow valve 36. Similarly, the secondary pipeline system 20 comprises a sixth flow valve 38, a second flow controller 40, a second pressure gauge 42, a seventh flow valve 44, an eighth flow valve 46, a ninth flow valve 48, a second pressure controller 50 and a tenth flow valve 52.
On entering the pipeline system 10, helium from the supply device 12 first arrives at the first flow valve 22 and the sixth flow valve 38. The helium then moves on to the first flow controller 24 and the second flow controller 40 along separate paths. The helium next moves on to the second flow valve 28 and the seventh flow valve 44, and then enters the operational device 14 next to the lower electrode for cooling the back surface of a silicon chip. The third flow valve 30 and the eighth flow valve 46 are connected to a point between the operational device 14 and the second flow valve 28 and between the operational device 14 and the seventh flow valve 44, respectively. The third and the eighth flow valve 30 and 46 are connected to an external pipeline, which serves as a standby system. In general, the standby system is unused if supporting software programs are unavailable. The first pressure gauge 26 and the second pressure gauge 42 are attached to a point between the first flow controller 24 and the second flow valve 28 and a point between the second flow controller 40 and the seventh flow valve 44, respectively. The pressure gauges 26 and 42 are used for detecting any variation in helium pressure inside the pipeline. The first pressure controller 34 and the second pressure controller 50 are used to control helium pressure inside the pipeline. The fourth flow valve 32 is connected to the second flow valve 28, the first flow controller 24, the first pressure gauge 26 and the first pressure controller 34. Similarly, the ninth flow valve 48 is connected to the seventh flow valve 44, the second flow controller 40, the second pressure gauge 42 and the second pressure controller 50. The fourth flow valve 32 and the ninth flow valve 48 are used for controlling the flow of helium to the first pressure controller 34 and the second pressure controller 50, respectively. Finally, output of helium to the extraction device 16 is controlled by the fifth flow valve 36 (connected to the first pressure controller 34) and the tenth flow valve 52 (connected to the second pressure controller 50), respectively.
The first pressure gauge 26 and the second pressure gauge 42 are separated from the operational device 14 by the second flow valve 28 and the seventh flow valve 77, respectively. Furthermore, the second flow valve 28 and the fourth flow valve 32 form a group while the seventh flow valve 44 and the ninth flow valve 48 form another group. The valves in each group open and close together so that a normal flow of helium can be maintained inside the pipeline. However, when the fourth flow valve 32 and the ninth flow valve 48 malfunction, the helium dumping loop is blocked. Hence, the fluid delivering system will trip due to the buildup of excess internal pressure. Similarly, malfunction in other pipeline components can be detected by the pressure gauges 26 and 42.
If the second flow valve 28 and the seventh flow valve 44 malfunction, helium supply to the operation device 14 will be cut. Consequently, the back surface of the silicon wafer will overheat, possibly leading to material burnt-out. However, the helium loop (for example, the main system pipeline 18) from the supply device 12 to the first flow valve 22, the first flow controller 24, the fourth flow valve 32, the first pressure controller 34 and the fifth flow valve 36 will remain open. Therefore, the first pressure gauge 26 or any other sensor installed along this helium loop will be unable to detect any abnormality. Since no abnormality in the helium pipeline is detected, no malfunctioning signals will be issued to terminate the current processing operation, even when no cooling helium is delivered to the back surface of the silicon wafer.